Electronic component package including stacked shield layers

ABSTRACT

The present invention provides an electronic component package including an electronic component mounted on a circuit board having a ground pattern, a mold containing an epoxy resin that encapsulates the electronic component, and a shield layer formed on the mold. The shield layer is formed by stacking a metal particle layer, a copper plating layer, and a nickel plating layer in this order from the mold side, and the shield layer is grounded to the ground pattern. The present invention also provides a method for manufacturing the electronic component package. The electronic component package is excellent in the adhesion of the shield layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.16/962,300, filed on Jul. 15, 2020, which is a 371 of InternationalApplication No. PCT/JP2019/006474, filed on Feb. 21, 2019, which isbased upon and claims the benefit of priority from the prior JapanesePatent Application No. 2018-033326, filed on Feb. 27, 2018.

TECHNICAL FIELD

The present invention relates to an electronic component package and amethod for manufacturing the same.

BACKGROUND ART

In recent years, in a portable information terminal such as asmartphone, a semiconductor package called a system-in-package (SiP),which operates as one functional block by mounting an IC and a largenumber of electronic components on one semiconductor package, has beenwidely used. Such a semiconductor package is provided with acountermeasure against electromagnetic wave noise so as to preventmalfunction due to external noise and prevent itself from becoming anoise source. For example, although not related to a system-in-package,PTL 1 discloses an electronic component package including a plurality ofplating layers as layers for shielding electromagnetic wave noise.

However, in the above-described electronic component package, althoughthe plating layer is directly provided as a shield layer on a mold inwhich the electronic component is encapsulated, there is a disadvantagethat the plating layer is easily peeled off from the mold.

CITATION LIST Patent Literature

-   PTL 1: JP-A-2005-109306

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide an electronic componentpackage in which a copper plating layer and a nickel plating layer areprovided as a shield layer on a mold in which an electronic component isencapsulated, the electronic component package having excellent adhesionbetween the shield layer and the mold, and a method for manufacturingthe electronic component package.

Solution to Problem

As a result of intensive studies to solve the above-mentioned problems,the present inventors have found that an electronic component packageincluding a mold containing an epoxy resin for encapsulating anelectronic component and a shield layer formed on the mold, wherein theshield layer is formed by stacking a metal particle layer, a copperplating layer and a nickel plating layer in this order from the moldside, has remarkably excellent adhesion between the shield layer and themold and excellent electromagnetic wave shielding properties, and thusthe present invention has been completed.

That is, the present invention provides an electronic component packageincluding: an electronic component mounted on a circuit board having aground pattern; a mold containing an epoxy resin that encapsulates theelectronic component; and a shield layer formed on the mold, wherein theshield layer is formed by stacking a metal particle layer, a copperplating layer, and a nickel plating layer in this order from the moldside, and wherein the shield layer is grounded to the ground pattern,and a method for manufacturing the electronic component package.

Advantageous Effects of Invention

The electronic component package of the present invention can besuitably used as, for example, a semiconductor package provided with ashield layer for enhancing the shielding effect of electromagnetic wavenoise of a semiconductor device, or an integrated module in which aplurality of modules are densely mounted by integrating functions of ahigh-frequency module, a front-end module including a filter, acommunication module for transmission and reception, and the like intoone function.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the entire electronic component package with a shieldlayer.

FIG. 2 shows a cross section (A-A) of the electronic component packageof FIG. 1.

FIG. 3 shows a cross section of an electronic component package in whicha polymer layer is provided on the surface of a mold.

FIG. 4 shows a cross section of a state in which a polymer layer isprovided on the surface of a mold, a slit portion is formed along ascheduled division line, and a metal particle layer is provided thereon.Finally, a copper plating layer and a nickel plating layer aresequentially stacked on the metal particle layer to form the electroniccomponent package of the present invention.

DESCRIPTION OF EMBODIMENTS

The electronic component package of the present invention is anelectronic component package including: an electronic component mountedon a circuit board having a ground pattern; a mold containing an epoxyresin that encapsulates the electronic component; and a shield layerformed on the mold, wherein the shield layer is formed by stacking ametal particle layer, a copper plating layer, and a nickel plating layerin this order from the mold side, and wherein the shield layer isgrounded to the ground pattern.

The circuit board having the ground pattern preferably has a structurein which a part of the ground pattern is exposed on the surface of themold, and excellent electromagnetic wave shielding properties can beobtained by connecting a shield layer described later and the groundpattern.

In the circuit board having the ground pattern, the ground pattern and awiring pattern may be formed in at least two layers on a substrate madeof an insulating material such as glass epoxy resin. In addition, whenthe circuit board is formed of two or more layers, a structure in whichthe layers are electrically connected by via holes is preferable.

As the circuit board having the ground pattern, a circuit board formounting at least two semiconductor devices in a planar or threedimensional arrangement on a substrate made of an insulating material,or a circuit board for an integrated module in which a plurality ofmodules are densely mounted by integrating functions of a high-frequencymodule, a front-end module including a filter, a communication modulefor transmission and reception, and the like into one function may beused.

Examples of the material of the circuit board having the ground patterninclude an insulating material such as a glass epoxy resin, a liquidcrystal polymer, a fluororesin represented by polytetrafluoroethylene, asilicone resin, a polyimide resin, a photosensitive insulating materialsuch as a polyimide resin, or a polybenzoxazole resin, a buildup filmcontaining a thermosetting epoxy resin, and a buildup film containing aglass cloth. These materials may be used alone or in combination of twoor more kinds thereof as a substrate.

In the present invention, after an electronic component is mounted onthe circuit board having the ground pattern, a mold is formed of amaterial containing an epoxy resin. As the material containing the epoxyresin, a material obtained by curing a thermosetting epoxy resin with acuring agent such as a phenol-based curing agent, a cyanate ester-basedcuring agent, or an active ester-based curing agent, or a materialobtained by adding an inorganic filler represented by silica particlesto the thermosetting epoxy resin, which is generally used as anencapsulating material, can be used. Examples of the method of moldingthe mold include a transfer molding method and a compression moldingmethod, and a method of encapsulating the mold using an encapsulatingresin sheet with a laminator or a press apparatus.

In addition, the surface of the mold may be surface-treated by, forexample, a plasma discharge treatment method such as a corona dischargetreatment method; a dry treatment method such as an ultraviolettreatment method; or a wet treatment method using water, an acidic oralkaline chemical solution, an organic solvent, or the like in order tofurther improve the adhesion to a metal particle layer described lateror a polymer layer described later. Further, PTL 1 described abovedescribes roughening treatment of the surface of the mold with achemical agent, but in the present invention, it is preferable not toroughen the surface of the mold.

Next, in the present invention, a metal particle layer is provided toform a shield layer on the mold. The metal particle layer functions as aplating seed layer for bringing the mold and a copper plating layerdescribed later into close contact with each other and for forming thecopper plating layer described later, and is used as a catalyst forelectroless copper plating or a seed conductive layer for electrolyticcopper plating.

In the present invention, a polymer layer is preferably provided on themold and between the mold and the metal particle layer in order tofurther improve the adhesion between the mold and the shield layer.Examples of the polymer forming the polymer layer include various resinssuch as a urethane resin, a vinyl resin, an acrylic resin, aurethane-acrylic composite resin, an epoxy resin, an imide resin, anamide resin, a melamine resin, a phenol resin, a polyvinyl alcohol, anda polyvinyl pyrrolidone.

Among the resins used as the polymer, a urethane resin, an acrylicresin, a urethane-acrylic composite resin, and an epoxy resin arepreferable, and one or more resins selected from the group consisting ofa urethane resin having a polyether structure, a urethane resin having apolycarbonate structure, a urethane resin having a polyester structure,an acrylic resin, a urethane-acrylic composite resin, and an epoxy resinare more preferable. Further, the urethane-acrylic composite resin isstill more preferable because a wiring pattern excellent in adhesion andconductivity can be obtained.

When the metal particle layer is composed of metal particles dispersedby a polymer dispersant described later and the polymer dispersantcontains a compound (b1) having a reactive functional group [Y]described later, the polymer forming the polymer layer is preferably acompound (a1) having a functional group [X] having reactivity with thereactive functional group [Y]. Examples of the compound (a1) having thereactive functional group [X] include compounds having an amino group,an amide group, an alkylolamide group, a carboxyl group, an anhydrouscarboxyl group, a carbonyl group, an acetoacetyl group, an epoxy group,an alicyclic epoxy group, an oxetane ring, a vinyl group, an allylgroup, a (meth)acryloyl group, a (blocked) isocyanate group, an (alkoxy)silyl group or the like, and a silsesquioxane compound.

In particular, when the compound (b1) having a reactive functional group[Y] in the polymer dispersant described later of the metal particlelayer is a compound having a basic nitrogen atom-containing groupdescribed later, the polymer forming the polymer layer preferably has acarboxyl group, a carbonyl group, an acetoacetyl group, an epoxy group,an alicyclic epoxy group, an alkylolamide group, an isocyanate group, avinyl group, a (meth)acryloyl group, or an allyl group as the reactivefunctional group [X] because the adhesion between the finally obtainedmold and the shield layer can be further improved.

The polymer layer is preferably provided as a thin film on the entiresurface of the mold, but in order to connect the ground pattern of theelectronic component package and the shield layer, the polymer layer ispreferably provided avoiding the ground pattern exposed from the mold.In addition, it is preferable that the polymer layer is not formed in aportion where the shield layer of the electronic component package isnot formed. Examples of the portion where the shield layer of theelectronic component package is not formed include a circuit board sideopposite to the shield layer of the electronic component package, aportion where a solder ball is formed, and a portion where a solder ballis to be formed.

When the polymer forming the polymer layer is applied to the surface ofthe mold, a fluid in which the polymer is dissolved or dispersed in asolvent is used. Examples of the application method include a coatingmethod, a dipping method, a roller coating method, a spin coatingmethod, a rotary method, a spray method, a dispenser method, an inkjetprinting method, a pad printing method, a reverse printing method, aflexographic printing method, a screen printing method, a gravureprinting method, and a gravure offset printing method.

Further, when the fluid containing the polymer is applied, the fluid maybe applied after a portion where the polymer layer is not desired to beapplied is protected by a masking tape or a sealing material.

Next, the fluid containing the polymer is applied to form the polymerlayer and then dried. The drying is performed in order to volatilize asolvent contained in the fluid containing the polymer. The drying ispreferably performed in a temperature range of 80 to 300° C. for about 1to 200 minutes.

The thickness of the polymer layer formed using the polymer ispreferably in the range of 5 to 5,000 nm because the adhesion betweenthe mold and the metal particle layer described later can be furtherimproved, and more preferably in the range of 10 to 200 nm because thefinally obtained shield layer has excellent adhesion to the mold.

The metal particle layer forming the shield layer in the presentinvention is preferably composed of metal particles dispersed by apolymer dispersant because the metal particles have excellent adhesionto the mold or the polymer layer.

The polymer dispersant is preferably a polymer having a functional groupthat coordinates to the metal particles. Examples of the functionalgroup include a carboxyl group, an amino group, a cyano group, anacetoacetyl group, a phosphorus atom-containing group, a thiol group, athiocyanato group, and a glycinato group.

The polymer dispersant preferably contains the compound (b1) having areactive functional group [Y] in order to improve the adhesion to themold or the polymer layer.

The reactive functional group [Y] of the compound (b1) is involved inbonding with an epoxy group, a phenolic hydroxy group, or a hydroxygroup present in the mold, or the reactive functional group [X] in thepolymer. Specific examples of the compound (b1) include compounds havingan amino group, an amide group, an alkylolamide group, a carboxyl group,an anhydrous carboxyl group, a carbonyl group, an acetoacetyl group, anepoxy group, an alicyclic epoxy group, an oxetane ring, a vinyl group,an allyl group, a (meth)acryloyl group, a (blocked) isocyanate group, an(alkoxy) silyl group or the like, and a silsesquioxane compound.

In particular, the reactive functional group [Y] is preferably a basicnitrogen atom-containing group in order to further improve the adhesionto the mold or the polymer layer.

Examples of the basic nitrogen atom-containing group include an iminogroup, a primary amino group, and a secondary amino group.

In addition, by using a compound having a plurality of basic nitrogenatom-containing groups in one molecule as the compound (b1), one of thebasic nitrogen atom-containing groups is involved in bonding with theepoxy group present in the mold or the reactive functional group [X] ofthe polymer forming the polymer layer, and the other contributes tointeraction with the metal particles contained in the metal particlelayer, thereby further improving the adhesion between the finallyobtained metal plating layer described later and the mold, which ispreferable.

As the compound having a basic nitrogen atom-containing group, apolyalkyleneimine or a polyalkyleneimine having a polyoxyalkylenestructure containing an oxyethylene unit is preferable because thedispersion stability of the metal particles and the adhesion to thepolymer layer can be further improved.

The polyalkyleneimine having a polyoxyalkylene structure may be acompound in which polyethyleneimine and polyoxyalkylene are bonded in alinear form, or may be a compound in which the polyoxyalkylene isgrafted to a side chain of a main chain composed of thepolyethyleneimine.

Specific examples of the polyalkyleneimine having a polyoxyalkylenestructure include a block copolymer of polyethyleneimine andpolyoxyethylene, a compound in which a polyoxyethylene structure isintroduced by addition reaction of ethylene oxide to a part of iminogroups present in the main chain of polyethyleneimine, and a compound inwhich an amino group of polyalkyleneimine, a hydroxy group ofpolyoxyethylene glycol, and an epoxy group of an epoxy resin arereacted.

Examples of commercially available products of thepolyalkyleneimineinclude“PAO2006 W”, “PAO306”, “PAO318”, and “PAO718” of“EPOMIN (registered trademark) PAO series” manufactured by NipponShokubai Co., Ltd.

The number average molecular weight of the polyalkyleneimine ispreferably in the range of 3,000 to 30,000.

When the reactive functional group [Y] of the compound (b1) is acarboxyl group, an amino group, a cyano group, an acetoacetyl group, aphosphorus atom-containing group, a thiol group, a thiocyanato group, aglycinato group or the like, the compound (b1) can also be used as apolymer dispersant for metal particles because these functional groupsalso function as functional groups coordinating with metal particles.

Next, examples of the metal particles constituting the metal layerinclude transition metals and compounds thereof, and among thetransition metals, ionic transition metals are preferable. Examples ofthe ionic transition metal include metals such as copper, silver, gold,nickel, palladium, platinum, and cobalt, and complexes of these metals.These metal particles may be used alone or in combination of two or morekinds thereof. Further, among these metal particles, silver particlesare particularly preferable from the viewpoints of less problems inhandling such as oxidation deterioration and cost.

As the metal particles, it is preferable to use particulate particleshaving an average particle diameter of about 1 to 20,000 nm, and it ismore preferable to use metal nanoparticles having an average particlediameter of 1 to 200 nm because the copper plating deposition propertieswhen used as a catalyst for electroless copper plating and the electricresistance when used as a seed layer for electrolytic copper plating canbe further reduced in a copper plating step described later, comparedwith the case of using metal particles having an average particlediameter of micrometer order. In the present invention, the averageparticle diameter is a volume-average value measured by a dynamic lightscattering method after diluting the metal particle with a gooddispersion solvent. For this measurement, “Nanotrac UPA” manufactured byMicrotracBEL Corp. can be used.

In order to form the metal particle layer, the mold is preferablyapplied by various application methods described later, and for thispurpose, it is preferable to use a metal particle dispersion liquid inwhich metal particles are dispersed in various solvents. Examples of thesolvent include aqueous media such as distilled water, ion-exchangedwater, pure water, and ultrapure water; and organic solvents such asalcohol solvents, ether solvents, ketone solvents, and ester solvents.

Examples of the alcohol solvent or ether solvent include methanol,ethanol, n-propanol, isopropyl alcohol, n-butanol, isobutyl alcohol,sec-butanol, tert-butanol, heptanol, hexanol, octanol, nonanol, decanol,undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, stearylalcohol, allyl alcohol, cyclohexanol, terpineol, terpineol,dihydroterpineol, 2-ethyl-1,3-hexanediol, ethylene glycol, diethyleneglycol, triethylene glycol, polyethylene glycol, propylene glycol,dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,2,3-butanediol, glycerin, ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, ethylene glycol monobutyl ether, diethyleneglycol monoethyl ether, diethylene glycol monomethyl ether, diethyleneglycol monobutyl ether, tetraethylene glycol monobutyl ether, propyleneglycol monomethyl ether, dipropylene glycol monomethyl ether,tripropylene glycol monomethyl ether, propylene glycol monopropyl ether,dipropylene glycol monopropyl ether, propylene glycol monobutyl ether,dipropylene glycol monobutyl ether, and tripropylene glycol monobutylether.

Examples of the ketone solvent include acetone, cyclohexanone, andmethyl ethyl ketone. In addition, examples of the ester solvent includeethyl acetate, butyl acetate, 3-methoxybutyl acetate, and3-methoxy-3-methyl-butyl acetate. Further, examples of the other organicsolvent include hydrocarbon solvents such as toluene, particularlyhydrocarbon solvents having 8 or more carbon atoms.

Examples of the hydrocarbon solvent having 8 or more carbon atomsinclude nonpolar solvents such as octane, nonane, decane, dodecane,tridecane, tetradecane, cyclooctane, xylene, mesitylene, ethylbenzene,dodecylbenzene, tetralin, and trimethylbenzenecyclohexane, which can beused in combination with other solvents as necessary. Further, solventssuch as mineral spirits and solvent naphtha, which are mixed solvents,may be used in combination.

The metal particle dispersion liquid can be produced, for example, bymixing the polymer dispersant, the metal particles, and if necessary,the solvent. Specifically, it can be produced by adding a previouslyprepared ionic solution of the metal to a medium in which a compoundhaving a polyalkyleneimine chain, a hydrophilic segment, and ahydrophobic segment is dispersed, and reducing the metal ion.

In addition, in order to improve the dispersion stability of theconductive material in a solvent such as an aqueous medium or an organicsolvent and the wettability to the surface to be applied, a surfactant,an anti-foaming agent, a rheology modifier, and the like may be added tothe metal particle dispersion liquid as necessary.

The metal particle layer may be provided as a thin film on the entiresurface and the side surface of the mold. However, in order to connectthe ground pattern of the electronic component package and the shieldlayer, the metal particle layer needs to be provided so as to be incontact with the ground pattern exposed from the mold. In addition, itis preferable that the metal particle layer is not formed in a portionwhere the shield layer of the electronic component package is notformed. Examples of the portion where the shield layer of the electroniccomponent package is not formed include a portion on the side oppositeto the shield layer of the electronic component package where a solderball is formed, a portion where the solder ball is to be formed, and thelike.

The metal particle layer may be provided on the entire surface of aportion of the mold where the shield layer is to be formed, or a patternmay be formed by applying the metal particle dispersion liquid by anapplication method described later. When the pattern is formed by themetal particle layer, a copper plating layer and a nickel plating layerdescribed later are formed only on the pattern of the metal particlelayer, and thus the shield layer itself can be patterned. The pattern ofthe metal particle layer may form a portion without the metal particlelayer as long as the electromagnetic wave shielding property is notimpaired. For example, a pattern in which holes are formed in a dotshape in the metal particle layer, a pattern in which the metal particlelayer is arranged in a lattice shape, and other various patterns may beformed.

When the metal particle dispersion liquid is applied to the surface andthe side surface of the mold, examples of the application method includea coating method, a dipping method, a roller coating method, a spincoating method, a rotary method, a spray method, a dispenser method, aninkjet printing method, a pad printing method, a reverse printingmethod, a flexographic printing method, a screen printing method, agravure printing method, and a gravure offset printing method. When thepattern of the metal particle layer is formed, it is preferable to usean inkjet printing method, a pad printing method, a reverse printingmethod, a flexographic printing method, a screen printing method, agravure printing method, or a gravure offset printing method.

Among the application methods, it is particularly preferable to selectan application method for uniformly forming a thin metal particle layer,and it is preferable to select a dipping method, a spin coating method,a spray method, an inkjet printing method, or a flexographic printingmethod.

In addition, when the metal particle dispersion liquid is applied, themetal particle dispersion liquid may be applied after a portion wherethe metal particle layer is not formed is protected by a masking tape ora sealing material. Examples of the masking tape and the sealingmaterial include masking pressure-sensitive adhesive tapes for plating,masking tapes for printed circuit boards, dicing tapes used inprocessing semiconductor wafers, and thermal release sheets forelectronic component processes, and it is preferable to select amaterial capable of protecting the portion where the shield layer is notformed even in the metal plating step described later after the sealingmaterial is laid on the portion where the shield layer is not formed andthe metal particles are applied.

Next, the metal particle dispersion liquid is applied and dried to forma metal particle layer. The drying is performed in order to volatilizethe solvent contained in the metal particle dispersion liquid, or inorder to form a metal particle layer having conductivity by adhering andbonding the metal particles to each other in the case of using as aconductive layer of electrolytic copper plating described later. Thedrying is preferably performed in a temperature range of 80 to 300° C.for about 1 to 200 minutes. Here, in order to obtain a metal particlelayer (plating seed layer) having excellent adhesion to the mold or thepolymer layer, the drying temperature is more preferably set in therange of 100 to 200° C.

The drying may be performed in the air, but in order to prevent all ofthe metal particles from being oxidized, a part or all of the dryingstep may be performed in a reducing atmosphere.

In addition, the drying step may be performed using, for example, anoven, a hot air drying furnace, an infrared drying furnace, laserirradiation, microwave, light irradiation (flash irradiation device), orthe like.

It is preferable that the metal particle layer formed using the metalparticle dispersion liquid by the method as described above contains aconductive material in the range of 80 to 99.9% by mass and contains apolymer dispersant in the range of 0.1 to 20% by mass in the pattern.

The thickness of the metal layer formed by using the metal particledispersion liquid is preferably in the range of 5 to 500 nm because theactivity as a plating catalyst (plating deposition property) in anelectroless copper plating step described later and the electricresistance as a conductive layer in an electrolytic copper plating stepcan be reduced.

The copper plating layer constituting the shield layer of the presentinvention is used for shielding electric field noise. Examples of themethod for forming the copper plating layer include wet plating methodssuch as electroless copper plating and electrolytic copper plating, andthe copper plating layer may be formed by combining these platingmethods. For example, a method of performing electroless copper platingusing the metal particle layer as an electroless copper plating catalystand performing electrolytic copper plating using the electroless copperplating layer as a conductive layer, or electrolytic copper platingusing the metal particle layer as a conductive layer can be used.

Among the plating methods, an electrolytic copper plating method is morepreferable because the adhesion between the metal particle layer and thecopper plating layer formed by the plating method is further improvedand the productivity of the copper plating step is excellent.

The electroless plating method is, for example, a method in which anelectroless copper plating solution is brought into contact with themetal particle layer to deposit a copper metal contained in theelectroless copper plating solution, thereby forming an electrolesscopper plating layer composed of a metal film.

Examples of the electroless copper plating solution include a solutioncontaining copper, a reducing agent, and a solvent such as an aqueousmedium or an organic solvent.

Examples of the reducing agent include dimethylaminoborane,hypophosphorous acid, sodium hypophosphite, dimethylamine borane,hydrazine, formaldehyde, sodium borohydride, and phenol.

As the electroless copper plating solution, as necessary, it is possibleto use a complexing agent such as a monocarboxylic acid such as aceticacid and formic acid; a dicarboxylic acid compound such as malonic acid,succinic acid, adipic acid, maleic acid, and fumaric acid; ahydroxycarboxylic acid compound such as malic acid, lactic acid,glycolic acid, gluconic acid, and citric acid; an amino acid compoundsuch as glycine, alanine, iminodiacetic acid, arginine, aspartic acid,and glutamic acid; an organic acid such as an amino polycarboxylic acidcompound such as iminodiacetic acid, nitrilotriacetic acid,ethylenediaminediacetic acid, ethylenediaminetetraacetic acid, anddiethylenetriaminepentaacetic acid, or a soluble salt (sodium salt,potassium salt, ammonium salt, and the like) of the organic acidthereof; and an amine compound such as ethylene diamine, diethylenetriamine, and triethylene tetramine.

The electroless copper plating solution is preferably used in the rangeof 20 to 98° C.

The electrolytic copper plating method is, for example, a method offorming an electrolytic copper plating layer by causing a metal such ascopper contained in an electrolytic copper plating solution to depositon the surface of the metal particle layer provided on a cathode or theelectroless copper plating layer formed by the electroless copperplating by applying an electric current in a state where theelectrolytic copper plating solution is in contact with the surface ofthe metal constituting the metal particle layer or the electrolesscopper plating layer formed by the electroless copper plating.

Examples of the electrolytic copper plating solution include a solutioncontaining a sulfide of copper, sulfuric acid, and an aqueous medium.Specific examples thereof include a solution containing copper sulfate,sulfuric acid, and an aqueous medium.

The electrolytic copper plating solution is preferably used in the rangeof 20 to 98° C.

As the method of the plating treatment, an electrolytic copper platingmethod is preferable because a highly toxic substance is not used andworkability is good. In addition, the electrolytic copper plating ispreferable because the plating time can be shortened and the control ofthe film thickness of the plating is easy, as compared with theelectroless copper plating.

The thickness of the copper plating layer formed by the copper platingmethod is preferably in the range of 0.5 to 30 μm because of excellentelectric field shielding properties. When the copper plating layer isformed by the electrolytic copper plating method, the thickness of thelayer can be adjusted by controlling the treatment time, the currentdensity, the amount of the plating additive used, and the like in theplating treatment step.

The nickel plating layer constituting the shield layer of the presentinvention is used for shielding magnetic field noise. The nickel platinglayer is also used to prevent oxidation deterioration and corrosion ofthe surface of the copper plating layer. Examples of the method forforming the nickel plating layer include wet plating methods such aselectroless nickel plating and electrolytic nickel plating, and thenickel plating layer may be formed by combining these plating methods.The nickel layer is preferably formed by electrolytic nickel platingbecause of excellent magnetic field shielding properties.

A plating layer of another metal may be stacked on the nickel platinglayer. For example, when a gold plating layer, a tin plating layer, or achromium plating layer is provided, corrosion of the surface of thenickel plating layer can be prevented. Further, the metal particle layermay be formed as a protective film on the nickel plating layer. Examplesof the metal particle layer include a silver nanoparticle layer.Further, a resin film may be formed as a protective film on the nickelplating layer. Examples of the resin film include the resins exemplifiedas the polymer layer.

The thickness of the nickel plating layer formed by the nickel platingmethod is preferably in the range of 0.5 to 10 μm because of excellentmagnetic field shielding properties.

Next, a method for manufacturing the electronic component package of thepresent invention will be described. Examples of the manufacturingmethod include a manufacturing method including: applying a dispersionliquid having metal particles to a surface of a mold of an electroniccomponent package having an electronic component mounted on a circuitboard having a ground pattern and the mold containing an epoxy resinthat encapsulates the electronic component and drying the dispersionliquid to form a metal particle layer; forming a copper plating layer onthe metal particle layer by using at least one selected from the groupconsisting of electroless copper plating and electrolytic copperplating; forming a nickel plating layer by using at least one selectedfrom the group consisting of electroless nickel plating and electrolyticnickel plating; and forming a shield layer having the metal particlelayer, the copper plating layer, and the nickel plating layer.

Here, as the manufacturing method, a manufacturing method in which apolymer layer is formed by applying and drying a fluid containing apolymer on the surface of the mold, a metal particle layer is formed byapplying and drying a dispersion liquid containing metal particles onthe polymer layer, and then the shield layer having the copper platinglayer and the nickel plating layer is formed is preferable because theadhesion between the mold and the shield layer is excellent.

The polymer layer is preferably provided as a thin film on the entiresurface of the mold, but in order to connect the ground pattern and theshield layer of the electronic component package, the polymer layer ispreferably provided avoiding the ground pattern exposed from the mold.In addition, it is preferable that the polymer layer is not formed in aportion where the shield layer of the electronic component package isnot formed. Examples of the portion where the shield layer of theelectronic component package is not formed include a circuit board sideopposite to the shield layer of the electronic component package, aportion where a solder ball is formed, and a portion where a solder ballis to be formed.

As a method of forming the metal particle layer on the surface of themold or on the polymer layer, a method of applying or printing a metalparticle dispersion liquid and a method of drying may be carried out bythe above-exemplified methods, and in the case where the metal particlesare nanoparticles such as silver nanoparticles, the above-describeddrying method can fuse the metal particles to form a conductive layerwhich functions as a plating seed layer in the electrolytic plating,which is preferable.

As a method of forming the polymer layer on the surface of the mold, amethod of applying or printing a fluid containing a polymer and a methodof drying may be carried out by the above-exemplified methods, and thepolymer layer may be formed by heat-curing the polymer or curing thepolymer with ultraviolet rays as necessary.

In the method of manufacturing the electronic component package, themethod of forming the shield layer before singulating the electroniccomponent package may include forming the polymer layer, dicing apart ofthe mold from above the polymer layer so as to expose the ground patternto form a slit portion in a scheduled division line, forming the metalparticle layer on a surface of the polymer layer and a diced surface ofthe slit portion, stacking the copper plating layer and the nickelplating layer to form the shield layer, and singulating the electroniccomponent using the slit portion.

The above-described manufacturing method is preferable because theshield layer can be efficiently manufactured on a large number ofelectronic component packages and productivity is excellent.

Here, the slit portion formed in the scheduled division line is providedto connect the ground pattern included in the circuit board of theelectronic component package and the shield layer formed of the metalparticle layer, the copper plating layer, and the nickel plating layer.When the metal particle layer is formed, a fluid containing metalparticles is preferably applied so as to be in contact with the groundpattern to form the metal particle layer.

The slit portion formed in the scheduled division line may be formedafter the electronic component package is fixed to a support before orafter the electronic component package is encapsulated. The support maybe the same as a temporary fixing substrate described later.

In addition, in the method of manufacturing the electronic componentpackage, the method of forming the shield layer after singulating theelectronic component package may include forming the polymer layer,singulating the electronic component encapsulated with the mold bydicing from above the polymer layer, temporarily fixing the singulatedelectronic component to a temporary fixing substrate, forming the metalparticle layer on a surface of the polymer layer of the singulatedelectronic component and a diced surface generated by dicing, stackingthe copper plating layer and the nickel plating layer to form the shieldlayer, grounding the shield layer to the ground pattern, and then takingout the singulated electronic component from the temporary fixingsubstrate.

Here, examples of the temporary fixing substrate include, as apressure-sensitive adhesive sheet or a pressure-sensitive adhesive filmobtained by pressure-sensitive adhesive processing on a support,fluororesin pressure-sensitive adhesive films using a fluororesin filmas a support, masking pressure-sensitive adhesive tapes for plating,masking tapes for printed circuit boards, dicing tapes used inprocessing semiconductor wafers, and thermal release sheets forelectronic component processes. The temporary fixing substrate can alsobe used for the purpose of protecting the portion where the shield layeris not formed.

Next, the method of forming a copper plating layer or a nickel platinglayer on a metal particle layer by electrolytic plating or electrolessplating can be carried out by the wet plating method as exemplifiedabove, and in particular, the electrolytic plating method is preferablyused from the viewpoints of productivity, mechanical properties of theobtained metal film, cost, and excellent magnetic field shieldingproperties in nickel plating.

The electronic component package of the present invention manufacturedin this manner can be used as an electronic component package in theapplications as exemplified above.

EXAMPLES

Hereinafter, the present invention will be described in detail withreference to examples.

Preparation Example 1: Preparation of Metal Particle Dispersion Liquid

Silver particles having an average particle diameter of 30 nm weredispersed in a mixed solvent of 30 parts by mass of ethylene glycol and70 parts by mass of ion-exchanged water using a compound obtained byadding polyoxyethylene to polyethylene imine as a dispersant, and thenion-exchanged water, ethanol, and a surfactant were added to adjust theviscosity to 10 mPa·s, thereby preparing a metal particle dispersionliquid. The metal particle dispersion liquid contains metal particlesand a polymer dispersant having a basic nitrogen atom-containing groupas a reactive functional group.

Production Example 1: Production of Resin for Polymer Layer

In a reaction vessel equipped with a stirrer, a reflux condenser, anitrogen inlet tube, and a thermometer, 100 parts by mass of apolycarbonate polyol (polycarbonate diol having an acid groupequivalence of 1,000 g/equivalent obtained by reacting1,4-cyclohexanedimethanol with a carbonate ester), 9.7 parts by mass of2,2-dimethylolpropionic acid, 5.5 parts by mass of1,4-cyclohexanedimethanol, and 51.4 parts by mass of dicyclohexylmethanediisocyanate were reacted in a mixed solvent of 111 parts by mass ofmethyl ethyl ketone, thereby obtaining an organic solvent solution of aurethane prepolymer having an isocyanate group at a molecular terminal.

Next, 7.3 parts by mass of triethylamine was added to the organicsolvent solution of a urethane resin to neutralize a part or all of thecarboxyl groups of the urethane resin, and 355 parts by mass of waterwas further added and sufficiently stirred to obtain an aqueousdispersion of the urethane resin.

Next, 4.3 parts by mass of a 25% by mass ethylenediamine aqueoussolution was added to the aqueous dispersion, stirred to chain-extendthe particulate polyurethane resin, followed by aging and solventremoval to obtain an aqueous dispersion of a urethane resin having asolid content concentration of 30% by mass.

A reaction vessel equipped with a stirrer, a reflux condenser, anitrogen inlet tube, a thermometer, a dropping funnel for dropping themonomer mixture, and a dropping funnel for dropping the polymerizationcatalyst was charged with 140 parts by mass of deionized water and 100parts by mass of the aqueous dispersion of a urethane resin obtainedabove, and the temperature was raised to 80° C. while blowing nitrogen.Into the reaction vessel heated to 80° C., a monomer mixture containing60 parts by mass of methyl methacrylate, 10 parts by mass of n-butylacrylate, and 30 parts by mass of N-n-butoxymethylacrylamide and 20parts by mass of an aqueous ammonium persulfate solution (concentration:0.5% by mass) were added dropwise with stirring from separate droppingfunnels over 120 minutes while maintaining the temperature in thereaction vessel at 80±2° C. to perform polymerization.

After completion of the dropwise addition, the mixture was stirred atthe same temperature for 60 minutes, and then the temperature in thereaction vessel was cooled to 40° C., deionized water was added so thatthe nonvolatile content became 20% by mass, and the mixture was filteredthrough a 200 mesh filter cloth to obtain a resin for a polymer layercontaining a carboxyl group and an N-n-butoxymethylacrylamide group asreactive functional groups.

Preparation Example 2: Preparation of Fluid Containing Resin for PolymerLayer

To 10 parts by mass of the resin for a polymer layer obtained in the“Production of Resin for Polymer Layer”, 90 parts by mass of ethanol wasstirred and mixed to obtain a fluid containing the resin for a polymerlayer.

Example 1

An electronic component mounted on a circuit board having a groundpattern is encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. The metal particle dispersion liquid prepared in PreparationExample 1 was applied to the surface of the mold by a spray device (aspray device equipped with a spray tip QTKA (flow rate size: 0.1 L/min)of a spray nozzle manufactured by Spraying Systems Co.) so that the filmthickness of a metal particle layer after drying became 150 nm.Thereafter, by drying at 180° C. for 10 minutes, a metal particle layerwas formed. The surface resistance value of the metal particle layer was4Ω/□.

Next, on the metal particle layer formed in the above-described manner,a phosphorus-containing copper was set as an anode, and electrolyticcopper plating was performed for 10 minutes at a current density of 2.5A/dm² using an electrolytic plating solution containing copper sulfate,whereby a copper plating layer having a thickness of 5 μm was stacked onthe surface of the metal particle layer. As the electrolytic copperplating solution, 70 g/L of copper sulfate, 200 g/L of sulfuric acid, 50mg/L of chlorine ions, and 5 mL/L of an additive (“Top Lucina SF-M”manufactured by Okuno Chemical Industries Co., Ltd.) were used.

Next, a 2 μm-thick nickel plating layer was stacked on the copperplating layer formed in the above-described manner by performingelectrolytic nickel plating on the copper plating layer at a currentdensity of 2 A/dm² for 5 minutes while supplying nickel ions with nickelsulfate to form a shield layer.

Example 2

An electronic component mounted on a circuit board having a groundpattern is encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. The fluid containing the resin for a polymer layer prepared inPreparation Example 2 was applied to the surface of the mold by a spraydevice (a spray device equipped with a spray tip QTKA (flow rate size:0.1 L/min) of a spray nozzle manufactured by Spraying Systems Co.) sothat the film thickness of a polymer layer after drying became 200 nm.Thereafter, by drying at 150° C. for 10 minutes, a polymer layer wasformed.

Next, the metal particle dispersion liquid prepared in PreparationExample 1 was applied onto the polymer layer formed in theabove-described manner by a spray device (a spray device equipped with aspray tip QTKA (flow rate size: 0.1 L/min) of a spray nozzlemanufactured by Spraying Systems Co.) so that the film thickness of ametal particle layer after drying became 150 nm. Thereafter, by dryingat 180° C. for 10 minutes, a metal particle layer was formed. Thesurface resistance value of the metal particle layer was 4Ω/□.

Next, electrolytic copper plating and electrolytic nickel plating wereperformed on the metal particle layer which was formed in theabove-described manner in the same manner as in Example 1 to form ashield layer formed of a copper plating layer having a thickness of 5 μmand a nickel plating layer having a thickness of 2 μm.

Example 3

An electronic component mounted on a circuit board having a groundpattern is encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. Next, a masking pressure-sensitive adhesive tape for platingwas attached to the circuit board side of the mold in which theelectronic component was encapsulated, on which the shield layer was notformed. Then, the fluid containing the resin for a polymer layerprepared in Preparation Example 2 was applied to the surface of the moldby a spray device (a spray device equipped with a spray tip QTKA (flowrate size: 0.1 L/min) of a spray nozzle manufactured by Spraying SystemsCo.) so that the film thickness of a polymer layer after drying became200 nm. Thereafter, by drying at 150° C. for 10 minutes, a polymer layerwas formed.

Next, the surface of the polymer layer formed in the above-describedmanner was subjected to half-dicing along the scheduled division linewith a diamond blade of a dicing apparatus to form a slit portion. Itwas found that there was no polymer layer in the slit portion and theground line of the circuit board was exposed.

Next, the metal particle dispersion liquid prepared in PreparationExample 1 was printed on the mold obtained above, on which the polymerlayer was formed and the slit portion was formed by half-dicing. Themetal particle dispersion liquid was printed using an ink jet printer(ink jet tester EB100, printer head KM512L for evaluation, dischargeamount 14 μL, manufactured by Konica Minolta IJ Inc.) first along theslit portion, and then the entire surface of the mold was printed.Thereafter, by drying at 150° C. for 10 minutes, a metal particle layerwas formed. The film thickness of the metal particle layer was 80 nm asan average film thickness at each portion.

Next, electroless copper plating was performed on the metal particlelayer formed in the above-described manner to form an electroless copperplating film having a thickness of 0.2 μm. The electroless copperplating was performed by preparing a bath of ARG copper (manufactured byOkuno Chemical Industries Co., Ltd.) under standard recommendedconditions (ARG copper 1: 30 mL/L, ARG copper 2: 15 mL/L, ARG copper 3:200 mL/L), keeping the bath temperature at 45° C., and immersing thesubstrate having the metal particle layer formed thereon for 15 minutesto deposit a copper plating film.

Next, electrolytic copper plating and electrolytic nickel plating wereperformed on the electroless copper plating layer which was formed inthe above-described manner in the same manner as in Example 1 to form ashield layer formed of a copper plating layer having a thickness of 5 μmand a nickel plating layer having a thickness of 2 μm.

Example 4

An electronic component mounted on a circuit board having a groundpattern is encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. Then, the fluid containing the resin for the polymer layerprepared in Preparation Example 2 was applied to the surface of the moldby a spray device (a spray device equipped with a spray tip QTKA (flowrate size: 0.1 L/min) of a spray nozzle manufactured by Spraying SystemsCo.) so that the film thickness of a polymer layer after drying became200 nm. Thereafter, by drying at 120° C. for 10 minutes, a polymer layerwas formed.

Next, the surface of the polymer layer formed in the above-describedmanner was diced along the division line into individual pieces eachhaving a length of 10 mm and a width of 10 mm with a diamond blade of adicing apparatus. It was found that there was no polymer layer in theportion of the singulated mold in contact with the diamond blade, andthe ground line of the circuit board was exposed. Next, 40 pieces of thesingulated mold were attached to the thermal release sheet forelectronic component process at a 2 mm interval.

Next, the metal particle dispersion liquid prepared in PreparationExample 1 was printed on the surface of the mold attached to the thermalrelease sheet for an electronic component process in the above-describedmanner. The metal particle dispersion liquid was also printed on thesurface of the mold, the side surface cut out by dicing, and the surfaceof the thermal release sheet for the electronic component process towhich the mold was attached, using an ink jet printer (ink jet testerEB100, printer head KM512L for evaluation, discharge amount 14 μL,manufactured by Konica Minolta IJ Inc.). Thereafter, by drying at 100°C. for 10 minutes, a metal particle layer was formed. The film thicknessof the metal particle layer was 90 nm as an average film thickness ateach portion.

Next, electroless copper plating was performed on the metal particlelayer formed in the above-described manner in the same manner as inExample 3 to form an electroless copper plating layer having a thicknessof 0.2 μm.

Next, electrolytic copper plating and electrolytic nickel plating wereperformed on the electroless copper plating layer which was formed inthe above-described manner in the same manner as in Example 1 to form ashield layer formed of a copper plating layer having a thickness of 5 μmand a nickel plating layer having a thickness of 2 μm.

Comparative Example 1

An electronic component mounted on a circuit board having a groundpattern is encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. In order to roughen the surface of the mold, the fillingmaterial in the mold was dissolved using hydrofluoric acid, androughening treatment was performed on the surface of the mold. For theroughening treatment, a chemical prepared by dissolving 150 g/L ofammonium fluoride in 1000 mL/L of 62% nitric acid was used. Theroughening treatment temperature was 40° C., and the rougheningtreatment time was 20 minutes.

Next, the mold subjected to the roughening treatment in theabove-described manner was immersed in a catalyst liquid made of astannous chloride protective colloid solution of palladium as anelectroless copper plating catalyst (aqueous solution containing 40 mL/Lof Catalyst C (trade name) manufactured by Okuno Chemical IndustriesCo., Ltd. and 180 mL/L of 35% hydrochloric acid) at 30° C. for 3minutes. Next, the electroless copper plating catalyst was activated byimmersing in an aqueous solution containing 100 mL/L of 98% sulfuricacid at 40° C. for 3 minutes.

Next, the mold subjected to the roughening treatment, the application ofthe electroless copper plating catalyst, and the activation treatment inthe above-described manner was subjected to electroless copper platingin the same manner as in Example 3 to form an electroless copper platinglayer having a thickness of 0.2 μm.

Next, electrolytic copper plating and electrolytic nickel plating wereperformed on the electroless copper plating layer which was formed inthe above-described manner in the same manner as in Example 1 to form ashield layer formed of a copper plating layer having a thickness of 5 μmand a nickel plating layer having a thickness of 2 μm.

Comparative Example 2

An electronic component mounted on a circuit board having a groundpattern was encapsulated with a semiconductor encapsulating resincomposition containing an epoxy resin, a phenol resin curing agent, anda filler. The surface of the mold was subjected to sputtering processaccording to a film forming method of magnetron sputtering. A copperfilm having a thickness of 0.2 μm was formed by this sputtering method.

Next, electrolytic copper plating and electrolytic nickel plating wereperformed on the copper film formed in the above-described manner in thesame manner as in Example 1 to form a shield layer formed of a copperplating layer having a thickness of 5 μm and a nickel plating layerhaving a thickness of 2 μm.

<Measurement of Adhesion (Peel Strength) of Shield Layer>

For each of the electronic component packages having the shield layerformed thereon obtained as described above, the peel strength betweenthe mold and the shield layer was measured using “Autograph AGS-X 500N”manufactured by Shimadzu Corporation. The lead width used for themeasurement was set to 1 mm, and the peel angle was set to 90°. Inaddition, the measurement of the peel strength in the present inventionwas carried out on the basis of the measured value when the thickness ofthe shield layer was 7 μm.

<Measurement of Adhesion (Peel Test) of Shield Layer after Heating>

Each of the electronic component packages having the shield layer formedthereon obtained as described above was stored and heated in a dryer setat 150° C. for 168 hours. After heating, the peel strength was measuredin the same manner as described above.

<Heat Resistance Evaluation>

Using the peel strength values before and after heating measured above,retention rates before and after heating were calculated, and heatresistance was evaluated according to the following criteria.

A: The retention rate is 80% or more.

B: The retention rate is 70% or more and less than 80%.

C: The retention rate is 50% or more and less than 70%.

D: The retention rate is less than 50%.

Table 1 shows the measurement results of the peel strength and theevaluation results of the heat resistance before and after heating withrespect to the shield layer of each of the electronic component packageshaving a shield layer formed therein which were obtained in Examples 1to 4 and Comparative Examples 1 and 2.

TABLE 1 Comparative Example 1 Example 2 Example 3 Example 4 Example 1Example 2 Roughening treatment of No No No No Yes No mold Polymer layerNo Yes Yes Yes No No Metal particle layer Silver Silver Silver Silver NoNo particle particle particle particle Sputtering layer No No No No NoCopper sputtering Evaluation Peel Before 350 560 600 610 180  150 results strength of heating stacked After 280 460 520 480 30 50 layer(N/m) heating Retention rate of  80  82  87  79 17 33 peel strength (%)Heat resistance A A A B D D

From the results shown in Table 1, it was found that the shield layersobtained in Examples 1 to 4, which are electronic component packages inwhich the shield layer of the present invention was formed, had a highpeel strength between the mold and the shield layer, a slight decreasein peel strength after heating, a high retention rate of peel strengthafter heating, and an excellent heat resistance.

On the other hand, the electronic component package having the shieldlayer formed thereon obtained in Comparative Example 1 is an example inwhich the mold was subjected to roughening treatment and then the metalplating film was formed, and it was found that the peel strength wasvery low before and after heating.

In addition, the electronic component package having the shield layerformed thereon obtained in Comparative Example 2 is an example in whicha metal layer was formed on a support using a sputtering method and thenmetal plating was performed, and it was found that the peel strength wasvery low before and after heating.

REFERENCE SIGNS LIST

-   -   1: Circuit board    -   2: Shield layer    -   3: Metal particle layer    -   4: Copper plating layer    -   5: Nickel plating layer    -   6: Ground pattern    -   7: Wiring pattern    -   8: Connection pad with another circuit board or the like    -   9: Electronic component such as semiconductor device    -   10: Polymer layer    -   11: Mold

1. An electronic component package comprising: an electronic componentmounted on a circuit board having a ground pattern; a mold containing anepoxy resin that encapsulates the electronic component; a polymer layerformed on a surface of the mold; and a shield layer formed on thepolymer layer, the shield layer comprising a metal particle layer, acopper plating layer, and a nickel plating layer in this order from thepolymer layer, wherein the shield layer is grounded to the groundpattern, wherein metal particles in the metal particle layer are coatedwith a polymer dispersant having a functional group coordinates to themetal particles.
 2. The electronic component package according to claim1, wherein the polymer dispersant has a reactive functional group [Y],and the polymer layer is a layer containing a polymer having a reactivefunctional group [X], wherein the reactive functional group [Y] and thereactive functional group [X] form a chemical bond.
 3. The electroniccomponent package according to claim 2, wherein the reactive functionalgroup [Y] is a basic nitrogen atom-containing group.
 4. The electroniccomponent package according to claim 2, wherein the polymer having thereactive functional group [Y] is at least one selected from the groupconsisting of a polyalkyleneimine and a polyalkyleneimine having apolyoxyalkylene structure including an oxyethylene unit.
 5. Theelectronic component package according to claim 2, wherein the reactivefunctional group [X] is at least one selected from the group consistingof a keto group, an acetoacetyl group, an epoxy group, a carboxyl group,an N-alkylol group, an isocyanate group, a vinyl group, a (meth)acryloylgroup, and an allyl group.
 6. The electronic component package accordingto claim 1, wherein the metal particle layer comprises 80-99.9% by massof metal particles and 0.1 to 20% by mass of the polymer dispersant. 7.The electronic component package according to claim 1, wherein the metalparticle layer consists of 80-99.9% by mass of metal particles and 0.1to 20% by mass of the polymer dispersant.